4-imino-oxazolidine-2-one derivatives, a process for producing such derivatives and a herbicide containing them as an active ingredient

ABSTRACT

The invention relates to 4-imino-oxazolidine-2-one derivatives represented by the general formula (1): ##STR1## and a process for producing said compounds by reacting aryl isocyanates of the general formula (2): ##STR2## with methacrolein cyanohydrin in the presence of a base, as well as a herbicide containing said compounds as an active ingredient; it also relates to a process for producing oxazolidinedione derivatives useful as herbicides by hydrolyzing said compounds.

TECHNICAL FIELD

The present invention relates to 4-imino-oxazolidine-2-one derivativesrepresented by the General formula (1): ##STR3## (where X¹ is a hydrogenatom or a halogen atom; X² is a hydrogen atom, a halogen atom or analkyloxy group, preferably having 1-6 carbon atoms; X³ is a hydrogenatom, a halogen atom, an alkyloxy group, preferably having 1-6 carbonatoms, a cycloalkyloxy group, preferably having 3-6 carbon atoms, or analkynyloxy group, preferably having 3-4 carbon atoms) or salts thereof,a process for producing such derivatives or salts thereof, and aherbicide containing such derivatives or salts thereof as an activeingredient. The present invention also relates to a process forproducing oxazolidinedione derivatives of the general formula (3) byhydrolyzing the imino group in position 4 of 4-imino-oxazolidine-2-onederivatives of the general formula (1) as follows: ##STR4## (were X¹, X²and X³ each have the same meaning as defined above).

BACKGROUND ART

Conventionally, 4-imino-oxazolidine-2-one derivatives having substitutedaryl groups on the nitrogen atom in position 3 are known to havefungicidal activity (see, for example, Japanese Patent Publication No.43800/1972); however, there have been no reports on the synthesis of4-imino-oxazolidine-2-one derivatives having an isopropylidene group inposition 5 of the oxazolidine ring as represented by the general formula(1) in the present invention and it is entirely unknown that suchderivatives have a potent herbicidal activity.

The 4-imino-oxazolidine-2-one derivatives described in Japanese PatentPublication No. 43800/1972 are produced by addition and cyclizationreactions of the corresponding isocyanate and cyanoalcohol. However, noreaction has yet been known that employs a cyanoalcohol having a doublebond in the a position and, what is more, the introduction of anisopropylidene group utilizing the isomerization of the double bond is areaction that is a key to the synthesis of the 4-imino-oxazolidine-2-onederivatives of the present invention.

EP-0241559B teaches that oxazolidinedione derivatives represented by thegeneral formula (3) are useful as the active ingredient of the herbicideit claims and such derivatives may be produced by subjecting an arylisocyanate (2) to an addition cyclization reaction with a2-hydroxy-3-methyl-3-butenoic acid ester (4) according to the schemeshown below. However, this process requires a two-step reaction forpreparing the 2-hydroxy-3-methyl-3-butenoic acid ester which is used asa starting material and it is necessary to use many auxiliary materials;what is more, the desired product cannot necessarily be obtained withsatisfactory yield.

Thus, the conventional method which uses the2-hydroxy-3-methyl-3-butenoic acid esters (4) not only involves aprolonged reaction process but also requires the use of many auxiliarymaterials in association with the individual steps and these and theadditional problem of low yield make the method economicallydisadvantageous for the production of oxazolidinedione derivatives ofthe general formula (3) which are useful as the active ingredient ofherbicides. Hence, it is desired to develop a more efficient productionprocess. ##STR5## (where X¹, X² and X³ each have the same meaning asdefined above; R' is a lower alkyl group).

DISCLOSURE OF INVENTION

The present inventors conducted intensive studies with a view to solvingthe aforementioned problems of the prior art and found the following:the novel oxazolidine-2-one derivatives of the invention which arerepresented by the general formula (1) set forth above and which have animino group in position 4 can be synthesized with high yield in a shortprocess by reacting the aryl isocyanate which is an inexpensive startingmaterial represented by the general formula (2) set forth above withmethacrolein cyanohydrin (1-cyano-2-methyl-2-propen-1-ol) in thepresence of a base; these compounds exhibit high herbicidal effectsagainst major weeds in low-dose treatments while causing low injury tomajor crops, thereby assuring excellent performance as herbicides; byhydrolyzing these compounds, specifically at the imino group in position4 under acidic conditions, oxazolidinedione derivatives of the generalformula (3) can be produced more economically than in the conventionalmethod. The present invention has been accomplished on the basis ofthese findings.

Thus, the present invention relates to 4-imino-oxazolidine-2-onederivatives represented by the general formula (1): ##STR6## (where X¹,X² and X³ each have the same meaning as defined above), and saltsthereof.

The present invention also relates to a process for producing4-imino-oxazolidine-2-one derivatives of the general formula (1):##STR7## (where X¹, X² and X³ each have the same meaning as definedabove) by reacting an aryl isocyanate of the general formula (2):##STR8## (where X¹, X² and X³ each have the same meaning as definedabove) with 1-cyano-2-methyl-2-propen-1-ol in the presence of a base.

The present invention also relates to a herbicide containing a4-imino-oxazolidine-2-one derivative of the general formula (1):##STR9## (where X¹, X² and X³ each have the same meaning as definedabove) or a salt thereof as an active ingredient.

The present invention further relates to a process for producing5-isopropyliden-2,4-oxazolidinedione derivatives of the general formula(3): ##STR10## (where X¹, X² and X³ each have the same meaning asdefined above) by hydrolyzing 4-imino-oxazolidine-2-one derivatives ofthe general formula (1): ##STR11## (where X¹, X² and X³ each have thesame meaning as defined above) under acidic conditions, as well as aprocess for producing 5-isopropyliden-2,4-oxazolidinedione derivativesof the general formula (3): ##STR12## (where X¹, X² and X³ each have thesame meaning as defined above) by first reacting an aryl isocyanate ofthe general formula (2): ##STR13## (where X¹, X² and X³ each have thesame meaning as defined above) with 1-cyano-2-methyl-2-propen-1-ol inthe presence of a base and then hydrolyzing the imino group under acidicconditions.

The halogen atom represented by X¹, X² and X³ in the4-imino-oxazolidine-2-one derivatives of the general formula (1) whichare the compounds of the present invention may be exemplified by afluorine atom, a chlorine atom, a bromine atom, etc.

The alkyloxy group represented by X² or X³ may be exemplified by amethoxy group, an ethoxy group, a propoxy group, an isopropoxy group, abutoxy group, an isobutoxy group, a pentyloxy group, a hexyloxy group,etc.

The cycloalkyloxy group represented by X³ may be exemplified by acyclopropyloxy group, a cyclopentyloxy group, a cyclohexyloxy group,etc. The alkynyloxy group may be exemplified by a propargyloxy group, a1-butyn-3-yloxy group, a 2-butynyloxy group, etc.

Salts of the derivatives (1) may be exemplified hydrochlorides,sulfates, phosphates, etc.

If the aryl isocyanate represented by the general formula (2) which isto be used in the production process of the invention is notcommercially available, it can be easily prepared by reacting thecorresponding aniline derivative with a phosgene or an equivalentthereof in the usual manner. The corresponding aniline derivative can beprepared by reference to a conventional method such as the one describedin Japanese Laid-Open Patent Application Nos. 17411/1993 or 43525/1993.

The 1-cyano-2-methyl-2-propen-1-ol can also be easily prepared by addinghydrocyanic acid to methacrolein (see Reference Examples 1 and 2 whichfollow).

The process of the present invention for producing4-imino-oxazolidine-2-one derivatives requires that the aryl isocyanate(2) be reacted with the 1-cyano-2-methyl-2-propen-1-ol in the presenceof a base. The base may be exemplified by organic amines such astriethylamine, tributylamine, N-methylmorpholine, pyridine anddimethylaniline, and alkali metal bases such as potassium carbonate,sodium carbonate, potassium hydrogencarbonate, sodium hydrogencarbonate,sodium hydride and sodium amide. The amount in which the base is to beused is not limited to any particular value and it may be a catalyticamount ranging from 1/100-1/10 of the substrate for the reaction.

The addition cyclization reaction of interest may be performed in theabsence of solvents but solvents that do no harm to the reaction mayalso be used, as exemplified by benzene, toluene, xylene, chlorobenzene,tetrahydrofuran, diethyl ether, diisopropyl ether, dimethoxyethane,hexane, octane, ethyl acetate, acetonitrile, acetone,N,N-dimethylformamide and N-methylpyrrolidone.

The process of generation of the 4-imino-oxazolidine-2-one derivatives(1) of the invention is shown by the following scheme: first, thehydroxyl group in 1-cyano-2-methyl-2-propen-1-ol is added to anisocyanato group to yield a carbamate derivative represented by thegeneral formula (5); thereafter, the nitrogen in the amide is cyclizedintramolecularly with the cyano group to form an intermediate (6) which,in turn, experiences a double bond shift to yield the4-imino-oxazolidine-2-one derivative (1): ##STR14##

As for the temperature for the respective reactions, there is no needfor heating in the reaction of adding 1-cyano-2-methyl-2-propen-1-ol tothe active aryl isocyanate (2) and the reaction will proceedsatisfactorily under low temperatures below room temperature. Thesubsequent intramolecular cyclization reaction is also believed to be avery rapid reaction from a standpoint of chemical kinetics and hencewill proceed at room temperature; however, this reaction can becompleted within a short time by performing it under heating at 30°-110°C., preferably about 40°-80° C. The reaction for the shift of a doublebond is believed to a thermodynamically controlled reaction and the rateof the reaction can be increased by performing it under heating; thereaction can be brought to a complete end by performing it under heatingranging from room temperature to 150° C., preferably from about 60° to110° C.

Thus, the production process of the invention yields the desired productby three different elementary reactions via the carbamate derivative (5)and the intermediate (6). In the process, these reactions are allowed toproceed sequentially under appropriate conditions, whereby the endproduct 4-imino-oxazolidine-2-one derivative (1) can be obtained throughone point without isolating the intermediates (5) and (6).

After completion of the reaction, the 4-imino-oxazolidine-2-onederivative (1) can be obtained by usual procedures. If desired, conc.HCl may be added to the obtained 4-imino-oxazolidine-2-one derivative(1) in solution, for example, in toluene so that the derivative isisolated as a hydrochloride. Needless to say, chemically acceptableother salts such as sulfates and phosphates are also included within thescope of the invention.

The thus obtained 4-imino-oxazolidine-2-one derivatives (1) may have theimino group in position 4-hydrolyzed to a carbonyl group under acidicconditions, whereby they can be easily converted to oxazolidinedionederivatives (3).

The hydrolytic reaction may be performed either by heating with 1-12NHCl being added to the 4-imino-oxazolidine-2-one derivative (1) or byheating with 1-12N HCl being added to the 4-imino-oxazolidine-2-onederivative (1) as it is dissolved in an organic solvent, so that thedesired oxazolidinedione derivative (3) can be produced.

The acid that can be used in the reaction may be exemplified byhydrochloric acid, sulfuric acid, phosphoric acid and other mineralacids and it is preferred to use hydrochloric acid which iscomparatively safe, easy to handle and inexpensive. Any organic solventsare usable as long as they are stable under acidic conditions and willdo no harm to the reaction and they may be exemplified by benzene,toluene, xylene, chlorobenzene, tetrahydrofuran, diethyl ether,diisopropyl ether, dimethoxyethane, ethyl acetate, acetonitrile,acetone, methanol, ethanol, etc.

The reaction may proceed at room temperature but if it is carried outunder heating, the reaction is completed within a short time to give thedesired product with high yield; hence, the reaction is preferablycarried out under heating at about 60°-150° C.

It should also be noted that in the production of the oxazolidinedionederivatives (3), there is no need to isolate the4-imino-oxazolidine-2-one derivatives (1) and after the additioncyclization reaction between the aryl isocyanate (2) and1-cyano-2-methyl-2-propen-1-ol, an acid may be added to the reactionsolution, which is hydrolyzed by heating under reflux to produce theoxazolidinedione derivatives (3).

The reactions at issue may be carried out successively under therespective appropriate reaction conditions using the solvents and acidsexemplified in connection with the already described production of the4-imino forms (1) and the reaction for their hydrolysis and thisprocedure is preferred since the desired product can be obtained withhigh yield.

The compounds of the present invention, when applied in soil and foliagetreatments on non-ricefields, show excellent herbicidal effects inlow-dose treatments against various noxious weeds including broadleafweeds such as Chenopodium album, Amaranthus viridis, Abutilontheophrasti and Stellaria media, and gramineous weeds such asEchinochloa crusgalli and Setaria viridis and yet cause no significantinjury to major crops including broadleaf crops such as soybean andcotton and gramineous crops such as corn. The compounds also showexcellent effects in low-dose treatments against various noxious weedsin ricefields including gramineous weeds such as Echinochloa oryzicola,broadleaf weeds such as Lindernia pyxidaria, Rotala indica and Elatinetriandra and sedge weeds such as Scirpus juncoides and Eleocharisacicularis and yet cause very slight injury to transplanted rice.

BEST MODE FOR CARRYING OUT THE INVENTION

The following Examples, Reference Examples and Test Examples areprovided for further illustrating the present invention but are in noway to be taken as limiting.

EXAMPLE 1 ##STR15##

A round-bottomed flask (500 cc) equipped with a dropping funnel wascharged with 4-chloro-5-cyclopentyloxy-2-fluorophenyl isocyanate (50.0g, 0.196 mol) and triethylamine (1.0 mL), as well as isopropyl ether(100 mL) and methacrolein cyanohydrin (15.0 g, 0.155 mol) was dropwiseadded slowly with stirring under cooling in an ice-water bath. After theaddition, the mixture was heated to room temperature and stirred at 50°C. for an additional 2 h. After completion of the reaction, theprecipitating crystal was recovered by filtration, washed with hexaneand dried to give3-(4-chloro-5-cyclopentyloxy-2-fluorophenyl)-4-imino-5-isopropylideneoxazolidine-2-oneas a pale yellow crystal (45.3 g; yield, 65.6%).

MP:131°-133° C.

¹ H-NMR(400 MHz, CDCl₃, TMS, ppm): δ1.64(2H, m), 1.89(6H, m), 2.03(3H,s), 2.30(3H, s), 4.74(1H, m), 6.82(1H, d, J_(HF) =5.15 Hz), 7.35(1H, d,J_(HF) =8.84 Hz).

IR(KBr disk, cm⁻¹): 2950, 1790, 1670, 1500, 1430, 1380, 1310, 1290,1230, 1190, 1130, 1050, 830, 750.

MS(m/e, relative intensity): 355(M⁺ +3, 1.40), 354(M⁺ +2, 4.54), 353(M⁺+1, 3.80), 352(M⁺, 13.74), 286(31.65), 284(90.37), 189(32.39),188(12.16), 187(100), 158(3.73), 70(82.44), 69(24.54), 42(34.86),41(84.61), 39(22.51), 28(14.20), 18(19.36).

EA (%, calcd. for C₁₇ H₁₈ ClFN₂ O₃): C; 57.86(57.87), H; 5.16(5.15), N;7.75(7.94).

The resulting3-(4-chloro-5-cyclopentyloxy-2-fluorophenyl)-4-imino-5-isopropylideneoxazolidine-2-onewas dissolved in toluene and conc. HCl (ca. 2 eq.) was added to thesolution at room temperature; the mixture was stirred thoroughly and theresulting white solids was subjected to filtration, washed thoroughlywith toluene and hexane and subsequently dried to yield3-(4-chloro-5-cyclopentyloxy-2-fluorophenyl)-4-imino-5-isopropylideneoxazolidine-2-onehydrochloride (compound 1) almost quantitatively.

MP:134°-135° C.

¹ H-NMR(400 MHz, DMSO₆ +D₂ O, TMS, ppm): δ1.72(2H, m), 1.74(4H,m),1.89(2H, m), 2.22(3H, s), 2.25(3H, s), 4.76(1H, m), 7.34(1H, d, J_(HF)=4.19 Hz ), 7.36(1H, d, J_(HF) =4.26 Hz).

IR(KBr disk, cm⁻¹): 2950, 1820, 1630, 1500, 1460, 1390, 1280, 1180,1140, 1050, 860, 750, 720.

EXAMPLE 2 ##STR16##

A round-bottomed flask (500 cc) equipped with a mechanical stirrer and adropping funnel was charged with4-chloro-5-cyclopentyloxy-2-fluorophenyl isocyanate (100 g, 0.392 mol)and toluene (100 mL) and, subsequently, a solution of methacroleincyanohydrin (35.0 g, 0.360 mol) and triethylamine (1.0 mL) in toluene(50 mL) was dropwise added slowly over 15 min with stirring undercooling in an ice-water-bath. After the addition, the mixture was heatedto room temperature and stirred at room temperature for an additional 4h, followed by washing with aqueous 1N sodium hydroxide (50 mL×2), 1NHCl (50 mL×2) and water (50 mL×2) and drying with anhydrous magnesiumsulfate. After removing the desiccant, the solvent was distilled offunder vacuum to give a brown crude product (124.5 g). A small amount ofhexane was added to the crude product and the precipitating crystal wasrecovered by filtration, washed with hexane and subsequently dried togive3-(4-chloro-5-cyclopentyloxy-2-fluorophenyl)-4-imino-5-isopropylideneoxazolidine-2-one(compound 2) as a pale yellow crystal (primary crystal; 53.9 g; yield,39.0%).

EXAMPLE 3 ##STR17##

A round-bottomed flask (200 cc) equipped with a dropping funnel wascharged with 4-chlorophenyl isocyanate (11.3 g, 73.7 mmol) andtriethylamine (0.5 mL), as well as isopropyl ether (40 mL) and toluene(30 mL) and methacrolein cyanohydrin (8.94 g, 92.1 mmol) was dropwiseadded slowly with stirring at room temperature. After the addition, themixture was stirred at room temperature for an additional 12 h. Aftercompletion of the reaction, the precipitating solids was recovered byfiltration, washed with ether (5 mL×2) and hexane (5 mL×2) andsubsequently dried to give3-(4-chlorophenyl)-4-imino-5-isopropylideneoxazolidine-2-one (compound3) as a white crystal (7.40 g; yield, 40.1%).

MP: 153°-155° C.

¹ H-NMR(400 MHz, CDCl₃, TMS, ppm): δ2.02(3H, s), 2.31(3H, s), 7.26(2H,d, J=8.66 Hz), 7.46(1H, br s), 8.57(2H, d, J=8.57 Hz).

IR(Kbr disk, cm⁻¹): 3250, 1770, 1660, 1490, 1410, 1290, 1260, 1200,1140, 1090, 1005, 840, 830, 750, 510.

MS(M/e, relative intensity): 253(M⁺ +3, 2.66), 252(M⁺ +2, 16.69), 251(M⁺+1, 7.40), 250(M⁺, 51.20), 155(21.93), 154(7.13), 153(67.75),125(16.78), 90(15.17), 70(100.0), 42(36.82), 41(25.73), 39(18.00),18(13.83).

EA(%, calcd. for C₁₂ H₁₁ ClN₂ O₂): C; 57.65(57.49), H; 4.22(4.43), N;11.34(11.18).

EXAMPLE 4 ##STR18##

A round-bottomed flask (100 cc) equipped with a dropping funnel wascharged with 2,4-dichlorophenyl isocyanate (2.66 g, 14.2 mmol) andtriethylamine (0.25 mL), as well as toluene (20 mL) and methacroleincyanohydrin (2.43 g, 25.0 mmol) was dropwise added slowly with stirringunder cooling in an ice-water bath. After the addition, the mixture washeated to room temperature and stirred at 50° C. for an additional 30min. After completion of the reaction, the reaction mixture was washedwith aqueous 1N sodium hydroxide (20 mL×2) and 1N HCl (30 mL) and driedwith magnesium sulfate; thereafter, the solvent was distilled off undervacuum to yield a crude product, which was recrystallized fromtoluene/hexane to give3-(2,4-dichlorophenyl)-4-imino-5-isopropylideneoxazolidine-2-one(compound 4) as a white crystal (1.92 g; yield, 47.4%).

MP: 129°-130° C.

¹ H-NMR(400 MHz, CDCl₃, TMS, ppm): δ2.03(3H, s), 2.28(3H, s),7.00-7.70(1H, br s), 7.29(1H, d, J=8.47 Hz), 7.44(1H, dd, J=8.47 Hz and2.25 Hz), 7.63(1H, d, J=2.25 Hz).

IR(KBr disk, cm⁻¹): 3360, 1780, 1660, 1490, 1410, 1280, 1210, 1135,1090, 1070, 1000, 820, 750, 740.

MS(m/e, relative intensity): 288(M⁺ +3, 3.08), 287(M⁺ +2, 3.15), 286(M⁺+1, 17.47), 285(M⁺, 5.03), 284(26.42), 189(18.59), 187(28.65),124(9.81), 70(100.0), 42(45.98), 41(28.65), 39(15.97), 18(17.89).

EA(%, calcd for C₁₂ H₁₀ Cl₂ N₂ O₂.1/4H₂ O): C; 49.80(49.76), H;3.36(3.66), N; 9.54(9.67).

EXAMPLE 5 ##STR19##

A round-bottomed flask (300 cc) equipped with a dropping funnel wascharged with 5-(1-methyl-2-propynyloxy)-4-chloro-2-fluorophenylisocyanate (10.0 g, 41.7 mmol) and triethylamine (1.0 mL), as well asisopropyl ether (40 mL) and diethyl ether (50 mL) and methacroleincyanohydrin (4.86 g, 50.0 mmol) was dropwise added slowly with stirringunder cooling in an ice-water bath. After the addition, the mixture washeated to room temperature and stirred for an additional 12 h. Aftercompletion of the reaction, the reaction mixture was poured into 1N HCl(50 mL) and extraction was conducted with ethyl acetate (50 mL×3). Theorganic layer was dried with magnesium sulfate and the solvent wassubsequently distilled off under vacuum to yield a crude product, whichwas purified by silica gel column chromatography (eluting solvents:ethyl acetate/hexane=1/5). The separated product of interest in turn wasrecrystallized from ether/hexane to give3-[5-(1-methyl-2-propynyloxy)-4-chloro-2-fluorophenyl]-4-imino-5-isopropylideneoxazolidine-2-one(compound 5) as a white crystal (7.37 g; yield, 52.4%).

Mp: 114°-115° C.

¹ H-NMR(400 MHz, CDCl₃, TMS, ppm): δ1.74(3H, d, J=6.57 Hz), 2.03(3H, s),2.29(3H, s), 2.57(1H, d, J=2.04 Hz), 4.84(1H, dq, J=6.57 Hz and 2.04Hz), 7.35(1H, d, J_(HF) =6.20 Hz), 7.38(1H, d, J_(HF) =8.95 Hz)

IR(KBr disk, cm⁻¹): 3300, 3200, 2100, 1800, 1675, 1505, 1430, 1385,1305, 1285, 1235, 1190, 1140, 1105, 1090, 1050, 1025, 870, 830, 750.

MS(m/e, relative intensity): 339(M⁺ +3, 1.84), 338(M⁺ +2, 9.74), 337(M⁺+1, 6.03), 336(M⁺, 28.62), 286(6.29), 285(7.69), 284(18.61), 283(16.55),189(12.19), 188(5.30), 187(36.63), 158(2.27), 70(100.0), 69(19.09),53(60.17), 42(54.76), 41(40.15), 27(40.27), 18(18.16).

EA(%, calcd. for C₁₆ H₁₄ ClFN₂ O₃): C; 56.81(57.06), H; 4.02(4.20), N;8.42(8.32).

EXAMPLE 6 ##STR20##

A round-bottomed flask (200 cc) equipped with a dropping funnel wascharged with 4-methoxyphenyl isocyanate (4.84 g, 32.5 mmol) andtriethylamine (0.5 mL), as well as isopropyl ether (30 mL) andmethacrolein cyanohydrin (4.50 g, 46.3 mmol) was dropwise added slowlywith stirring at room temperature. After the addition, the mixture wasstirred at room temperature for 12 h. After completion of the reaction,the reaction mixture was concentrated under vacuum to yield a crudeproduct, which was purified by silica gel column chromatography (elutingsolvents: ethyl acetate/hexane=1/5). The separated product of interestin turn was recrystallized from ether/hexane to give3-(4-methoxyphenyl)-4-imino-5-isopropylideneoxazolidine-2-one (compound6) as a white crystal (3.32 g; yield, 41.5%).

MP:119°-121° C.

¹ H-NMR(400 MHz, CDCl₃, TMS, ppm): δ2.02(3H, s), 2.30(3H, s), 3.86(3H,s), 7.05(2H, d, J=8.91 Hz), 7.21(2H, d, J=7.94 Hz, 7.39(1H, br s).

IR(KBr disk, cm⁻¹): 3250, 2950, 1780, 1660, 1510, 1435, 1400, 1290,1250, 1200, 1140, 1110, 1015, 870, 840, 755, 610.

MS(m/e, relative intensity): 247(M⁺ +1, 12.55), 246(M⁺, 67.87),218(3.52), 150(14.86), 149(100.00), 134(17.27), 106(7.64), 78(7.93),70(56.39), 42(27.87), 41(17.90), 28(10.76), 18(18.61).

EA(%, calcd. for C₁₃ H₁₄ N₂ O₃): C; 63.66(63.39), H; 5.72(5.74), N;11.37(11.38).

EXAMPLE 7 ##STR21##

A round-bottomed flask (100 cc) equipped with a dropping funnel wascharged with 3,4-dichlorophenyl isocyanate (1.41 g, 7.47 mmol) andtriethylamine (0.2 mL), as well as toluene (15 mL) and methacroleincyanohydrin (0.907 g, 9.34 mmol) was dropwise added slowly with stirringat room temperature. After the addition, the mixture was stirred at roomtemperature for 12 h. After completion of the reaction, theprecipitating solids was filtered off and thereafter the filtrate waswashed with aqueous 1N sodium hydroxide (5 ml), a saturated aqueoussolution of sodium hydrogensulfite (5 ml) and 1N HCl (5 ml). The organiclayer was dried with magnesium sulfate and thereafter the solvent wasdistilled off under vacuum to yield a crude product, which wasrecrystallized from toluene/hexane to give3-(3,4-dichlorophenyl)-4-imino-5-isopropylideneoxazolidine-2-one(compound 7) as a white crystal (0.820 g; yield, 38.6%).

MP: 132°-134° C.

¹ H-NMR(400 MHz, CDCl₃, TMS, ppm): δ2.03(3H, s), 2.31(3H, s), 7.15(1H,br s), 7.28(1H, d, J=8.47 Hz), 7.45(1H, dd, J=8.47 Hz and 2.27 Hz),7.65(1H, d, J=2.27 Hz).

IR(KBr disk, cm⁻¹): 3350, 3050, 1780, 1660, 1490, 1410, 1380, 1280,1210, 1135, 1090, 1065, 1000, 820, 780, 755, 740, 680.

MS(m/e, relative intensity): 288(M⁺ +3, 3.67), 287(M⁺ +2, 3.03), 286(M⁺+1, 20.23), 285(M⁺, 5.21), 284(31.62), 189(25.66), 187(39.97),124(13.43), 70(100), 42(37.55), 41 (25.81), 18(32.43).

EA(%, calcd. for C₁₂ H₁₀ Cl₂ N₂ O₂.1/4H₂ O): C; 49.89(49.76), H;3.50(3.66), N; 9.67(9.55).

EXAMPLE 8 ##STR22##

A round-bottomed flask (100 cc) equipped with a dropping funnel wascharged with 4-chloro-2-fluoro-5-isopropyloxyphenyl isocyanate (2.30 g,10.0 mmol) and triethylamine (0.1 mL), as well as toluene (10 mL) andmethacrolein cyanohydrin (1.07 g, 11.0 mmol) was dropwise added slowlyunder stirring at room temperature. After the addition, the mixture wasstirred at 80° C. for 2 h. After completion of the reaction, thereaction mixture was concentrated under vacuum and the resulting crudeproduct was purified by silica gel column chromatography (elutingsolvents: ethyl acetate/hexane=1/5) to yield3-(4-chloro-2-fluoro-5-isopropyloxyphenyl)-4-imino-5-isopropylideneoxazolidine-2-oneas a yellow oil (1.69 g). Subsequently, the imino form was dissolved intoluene (20 mL) under cooling with ice and 12N HCl (1 mL) was added. Awhite hydrochloride immediately formed and it was recovered byfiltration to give the desired product (compound 8) as white solids(0.881 g; yield, 26.9%).

MP: 201°-203° C.

¹ H-NMR(400 MHz, CDCl₃, DMSO-d₆): δ1.31(6H, d, J=5.93 Hz), 2.06(3H, s),2.30(3H, s), 4.53(1H, p, J=5.93 Hz), 7.54(1H, d, J_(HF) =6.68 Hz),7.79(1H, d, J_(HF) =9.39 Hz), 9.24(2H, br s).

IR(KBr disk, cm⁻¹): 3042, 2984, 2936, 2558, 2473, 1831, 1651, 1543,1507, 1470, 1391, 1215, 1186, 1146, 1109, 1051, 851.

EXAMPLE 9 ##STR23##

A round-bottomed flask (300 cc) was charged with3-(4-chloro-5-cyclopentyloxy-2-fluorophenyl)-4-imino-5-isopropylideneoxazolidine-2-one(17.5 g, 49.6 mmol), which was dissolved in isopropyl ether (40 mL).Then, conc. HCl (15 mL) was added and the mixture was heated underreflux for 3 h until all of the precipitating hydrochloride of the iminoform dissolved. After completion of the reaction, the reaction mixturewas transferred into a separating funnel and the organic layer wasseparated by addition of water. The organic layer was dried withanhydrous magnesium sulfate and thereafter the desiccant was removed andthe solvent was distilled off under vacuum. Hexane (15 mL) was added tothe resulting crude product and, upon standing at room temperature,3-(4-chloro-5-cyclopentyloxy-2-fluorophenyl)-5-isopropyliden-2,4-oxazolidinedioneprecipitated as a pale yellow crystal (13.28 g; yield, 79.3%), which wasisolated by filtration.

MP: 104.5°-105.0° C.

¹ H-NMR(CDCl₃, TMS, ppm): δ1.49-1.97(8H, m), 2.03(3H, s), 2.31(3H, s),4.73(1H, m), 6.88(1H, d, J_(HF) =6.6 Hz), 7.33(1H, d, J_(HF) =8.5 Hz).

IR(KBr disk, cm⁻¹): 2970, 1815, 1740, 1500, 1200.

EXAMPLE 10 ##STR24##

A round-bottomed flask (200 cc) was charged with4-chloro-5-cyclopentyloxy-2-fluorophenyl isocyanate (2.07 g; 8.10 mmol)and triethylamine (0.5 mL), as well as isopropyl ether (20 mL) andmethacrolein cyanohydrin (1.65 g, 17.0 mmol) was dropwise added slowlywith stirring under cooling in an ice-water bath. After the addition,the mixture was heated to room temperature and, after further additionof triethylamine (0.5 mL), the mixture was stirred overnight as such.After confirming the production of an imino form by TLC, conc. HCl (10mL) was added and the mixture was heated with stirring at 60° C. for 2 huntil all of the precipitating hydrochloride of the imino formdissolved. After completion of the reaction, the reaction mixture wastransferred into a separating funnel and washed successively withaqueous 1N sodium hydroxide and 1N HCl. The organic layer was dried withanhydrous magnesium sulfate and thereafter the desiccant was removed andthe solvent was distilled off under vacuum. The resulting crude productwas purified by silica gel column chromatography (eluting solvents:ethyl acetate/hexane=1/10) and then recrystallized from toluene/hexaneto give3-(4-chloro-5-cyclopentyloxy-2-fluorophenyl)-5-isopropyliden-2,4-oxazolidinedioneas a white crystal (1.73 g; yield, 63.2%).

EXAMPLE 11 ##STR25##

A round-bottomed flask (3000 cc) equipped with a mechanical stirrer wascharged with 4-chloro-5-cyclopentyloxy-2-fluorophenyl isocyanate (215 g,0.84 mol), triethylamine (5.4 mL) and solvent toluene (1000 mL) andmethacrolein cyanohydrin (102 g, 1.05 mol) was dropwise added slowlywith stirring at room temperature. After the addition, the mixture washeated to 40° C. and stirred for 2 h. Subsequently, conc. HCl (200 mL)was added to the stirred mixture, whereupon an imino form precipitatedas a hydrochloride, which was heated as such up to 110° C. and stirredfor 2.5 h. The reaction mixture was cooled to about 40° C. andthereafter aqueous 5N sodium hydroxide (325 mL) was added, followed bystirring at 50° C. for 2 h. After completion of the reaction, theorganic layer was separated from the resulting mixture and the aqueouslayer was subjected to extraction with toluene (200 mL×2). The organiclayers were combined and washed successively with aqueous 1N sodiumhydroxide (100 mL×2), 1N HCl (200 mL×2) and water (300 mL). The organiclayers were dried with anhydrous magnesium sulfate and thereafter thedesiccant was removed and the solvent was distilled off under vacuum.Hexane (ca. 300 mL) was added to the resulting brown oil and the mixturewas left to stand at room temperature. The precipitating crystal wasisolated by filtration and dried thoroughly to give3-(4-chloro-5-cyclopentyloxy-2-fluorophenyl)-5-isopropyliden-2,4-oxazolidinedioneas a white crystal (184 g; yield, 62.0%).

EXAMPLE 12 ##STR26##

A round-bottomed flask (3000 cc) equipped with a mechanical stirrer wascharged with 4-chloro-5-cyclopentyloxy-2-fluorophenyl isocyanate (206 g,0.81 mol), triethylamine (4.0 mL) and solvent toluene (900 mL) andmethacrolein cyanohydrin (97.8 g, 1.01 mol) was dropwise added slowlywith stirring at room temperature. After the addition, the mixture washeated to 40° C. and stirred for 1 h. Subsequently, conc. HCl (200 mL)was added to the stirred mixture, whereupon an imino form precipitatedas a hydrochloride, which was heated as such up to 110° C. and stirredfor 2 h. The reaction mixture was cooled to about 40° C. and thereafteraqueous 5N sodium hydroxide (250 mL) was added, followed by stirring at50° C. for 2 h. After completion of the reaction, the organic layer wasseparated from the resulting mixture and the aqueous layer was subjectedto extraction with toluene (50 mL×3). The organic layers were combinedand washed successively with aqueous 1N sodium hydroxide (1250 mL×4), 1NHCl (200 mL) and water (200 mL×2). The organic layers were dried withanhydrous magnesium sulfate and thereafter the desiccant was removed andthe solvent was distilled off under vacuum. A brown oil resulted towhich preliminarily prepared acidic methanol {MeOH (1400 mL/6 N HCl (5mL)} was added and the mixture was heated to form a homogeneoussolution; thereafter, 6N HCl (60 mL) was further added and the mixturewas left to stand so that it slowly cooled to room temperature. Theprecipitating crystal was isolated by filtration and dried thoroughly togive3-(4-chloro-5-cyclopentyloxy-2-fluorophenyl)-5-isopropyliden-2,4-oxazolidinedioneas a white crystal (216 g; yield, 75.7%).

EXAMPLE 13 ##STR27##

A round-bottomed flask (200 cc) was charged with4-chloro-5-cyclopentyloxy-2-fluorophenyl isocyanate (25.6 g, 0.10 ml),methacrolein cyanohydrin (10.5 g, 0.10 mol) and solvent toluene (70 mL)and triethylamine (0.10 g) was subsequently added at room temperature,followed by stirring at 80° C. for 3 h. The reaction mixture was cooledto room temperature and 17% HCl (80 mL) was added, whereupon an iminoform precipitated as a hydrochloride, which was heated as such andstirred under reflux for 2 h. After completion of the reaction, theorganic layer was separated from the resulting mixture and the aqueouslayer was subjected to extraction with toluene (20 mL×2). The organiclayers were combined and washed successively with aqueous 1N sodiumhydroxide and 1N HCl. The organic layers were dried with anhydrousmagnesium sulfate and thereafter the desiccant was removed and thesolvent was distilled off under vacuum. A brown oil resulted, to whichhexane (30 mL) was added and the mixture was left to stand at roomtemperature. The precipitating crystal was isolated by filtration anddried thoroughly to give3-(4-chloro-5-cyclopentyloxy-2-fluorophenyl)-5-isopropyliden-2,4-oxazolidinedioneas a white crystal (17.5 g; yield, 49.4%).

Reference Example 1 ##STR28##

A two-necked round-bottomed flask (3000 cc) was charged sodium cyanide(52.4 g, 1.07 mol) and diisopropyl ether (500 mL), and methacrolein(70.1 g, 1.00 mol) was added under cooling in an ice-water bath. Then,the mixture was stirred under cooling while conc. HCl (89 mL) wasdropwise added, at an insufficient rate for gases to evolve. After theaddition, the mixture was heated to room temperature and stirred for anadditional 1 h. After completion of the reaction (2 h later), thesupernatant was transferred into a separating funnel, washed with asaturated solution of sodium hydrogensulfite (10 mL×3) and dried withanhydrous magnesium sulfate. After removing the desiccant, the solventwas distilled off under vacuum to give a colorless clear solution ofmethacrolein cyanohydrin (92.5 g; yield, 95.2%).

BP: 86°-87° C./8 mmHg

¹ H-NMR(400 MHz, CDCl₃, TMS, ppm): δ1.91(3H, s), 3.25(1H, br s),4.88(1H, s), 5.14(1H, m), 5.33(1H, m).

IR(neat, cm⁻¹): 3450, 2950, 2275, 1660, 1450, 1390, 1090, 1060, 920

Reference Example 2 ##STR29##

A two-necked round-bottomed flask (200 cc) was charged sodium cyanide(2.50 g, 51.0 mmol) and diethyl ether (30 mL), and methacrolein (3.00 g,42.8 mmol) was added under cooling in an ice-water bath. Then, stirredconc. HCl (2.9 mL) was dropwise added slowly over 15 min under cooling.After the addition, the mixture was heated to room temperature andstirred for an additional 1 h. After completion of the reaction, thesupernatant was transferred into a separating funnel, washed with asaturated solution of sodium hydrogensulfite (5 mL×2) and dried withanhydrous magnesium sulfate. After removing the desiccant, the solventwas distilled off under vacuum to give a colorless clear solution ofmethacrolein cyanohydrin (3.27 g; yield, 78.7%).

The thus obtained compounds of the present invention have superiorherbicidal performance as already described herein. The compounds of theinvention may be used as herbicides on their own but more often than notthey are mixed with one or more adjuvants for use as herbicides. Commonadjuvants include various carriers, diluents, solvents, surfactants,stabilizers, etc., which are incorporated and preferably formulated insuitable forms such as a wettable powder, emulsifiable concentrate,dust, granules and a flowable by usual methods.

One of the adjuvants in the herbicides that contain the compounds of theinvention as an active ingredient is a solvent, suitable examples ofwhich include alcohols, ketones, ethers, aliphatic or aromatichydrocarbons, halogenated hydrocarbons, acid amides, esters, nitriles,etc.; these are used either alone or in admixture of two or more kinds.

Exemplary diluents that can be used include mineral powders includingclays such as kaolin and bentonite, talcs such as talc and pyrophylliteand oxides such as diatomaceous earth and white carbon, as well as plantpowders such as soybean meals and CMC. If desired, surfactants may beused as spreaders, dispersants, emulsifiers and penetrants. Thesurfactants may comprise nonionic surfactants, cationic surfactants,amphoteric surfactants, etc. These surfactants may be used either aloneor in admixture of two or more kids depending on the application.

Preferred methods of using herbicides containing the compounds of theinvention as an active ingredient include a soil treatment, awater-surface treatment and a foliage treatment and particularly goodresults can be achieved by application before the weeds to be controlledgerminate and up to the time when their seedlings emerge.

The herbicides containing the compounds of the invention as an activeingredient may be used in either admixture or combination with otheractive components that will not interfere with the herbicidal activityof the active ingredient of interest, such as other herbicides,insecticides, fungicides, plant growth regulators, etc.

The present invention will now be described in greater detail withreference to exemplary herbicidal formulations containing compounds ofthe invention as an active ingredient, as well as to the results of thereview of the herbicidal effect of the herbicide of interest. In thefollowing description, all "parts" are by weight.

Formulation Example 1 (Emulsifiable Concentrate)

A compound of the invention (20 parts), xylene (35 parts), cyclohexanone(40 parts) and Sorpol 900A (5 parts; Toho Chemical Industry) were mixeduniformly to prepare an emulsifiable concentrate.

Formulation Example 2 (Wettable Powder)

A mixture consisting of a compound of the invention (50 parts),diatomaceous earth (25 parts), clay (22 parts) and Lunox R100C (3 parts;Toho Chemical Industry) was evenly blended and ground to prepare awettable powder.

Formulation Example 3 (Granules)

A mixture consisting of a compound of the invention (5 parts), bentonire(35 parts), talc (55 parts) and sodium lingosulfonate (5 parts) wasevenly blended and ground, followed by kneading in the presence of addedwater and extrusion through a granulator to produce granules, which weresubsequently dried and screening to yield the finished granules.

Using the formulations prepared by the above described methods, theherbicidal effects of compounds of the present invention wereinvestigated in accordance with the methods described in the TestExamples that are set forth below, and the results are shown in Tables2-4. The growth inhibition of the plants under test was evaluated by thecriteria set forth in Table 1.

                  TABLE 1                                                         ______________________________________                                        Criteria for Evaluation                                                              Growth Inhibition                                                      ______________________________________                                               1      0%                                                                     2      25%                                                                    3      50%                                                                    4      75%                                                                    5      100%                                                            ______________________________________                                    

The compound used as a reference for comparison was commercialChlorphthalim (A) set forth below and it was formulated as herbicidalpreparations and applied for treatments in the same manner as thecompounds of the invention and its herbicidal activity and crop injurywere investigated by the same criteria for evaluation: ##STR30##

Test Example 1 (Effect on Weeds in Ricefields)

Pots of 1/5,000 were filled with the soil of ricefields, which was sownwith the seeds of Echinochloa oryzicola, Monochoria vaginalis, Scirpusjuncoides, Eleocharis acicularis and other annual broadleaf weeds andtransplanted with rice (variety: koshihikari) seedlings in the 2- or3-leaf stage and thereafter kept submerged with water. One day later,the wettable powders or emulsifiable concentrates of compounds of theinvention that were prepared in accordance with the Formulation Exampleswere diluted and dripped to give specified doses per are. On the 15thday after the treatment, the herbicidal effect on the plants under testand the injury to the rice plant were investigated in accordance withthe criteria for evaluation set forth in Table 1 and the results were asshown in Table 2.

                                      TABLE 2                                     __________________________________________________________________________    Effect of Pre-Emergence Soil Treatment in Ricefields                                  Herbicidal Effect                                                                        Other                                                          Dose           annual                Crop                                 Comp.                                                                             applied                                                                           Echinochloa                                                                         Cyperus                                                                            broadleaf                                                                          Monochoria                                                                          Scirpus                                                                            Eleocharis                                                                          injury                               No. g/a oryzicola                                                                           difformis                                                                          weeds                                                                              vaginalis                                                                           juncoides                                                                          acicularis                                                                          Rice                                 __________________________________________________________________________    1   2.5 4.5   5    5    5     4.2  5     1.2                                      1.0 4     5    5    5     4    5     1.1                                  2   2.5 5     5    5    5     4.5  5     1.3                                      1.0 4.8   5    5    5     4    4     1.2                                      0.5 3.5   4    4    4     3    3     1.1                                  5   2.5 5     5    5    5     5    5     1.2                                      1.0 4.9   5    5    5     5    5     1.1                                  A   2.5 5     5    5    5     5    --    5                                        1.0 5     5    5    5     4.8  --    3                                        0.5 3     5    4.8  5     4.5  --    1.5                                  __________________________________________________________________________

Test Example 2 (Effect by Soil Treatment in Non-Ricefields)

Vats each having an area of 10×10 cm² and a depth of 5 cm were filledwith the soil of non-ricefields, which was sown with Echinochloacrusgalli, Digitalia ciliaris, Amaranthus viridis, Chenopodium album andcorn, with the seeds being then covered with a soil layer 0.5 cm thick.On the next day, the wettable powders or emulsifiable concentrates ofcompounds of the invention that were prepared in accordance with theFormulation Examples were diluted and applied over the covering soillayer uniformly to give specified doses per are. On the 15th day afterthe treatment, the herbicidal effect on the weeds under text and theinjury to the corn were investigated in accordance with the criteria forevaluation set forth in Table 1 and the results were as shown in Table3.

                                      TABLE 3                                     __________________________________________________________________________    Effect in the Treatment of Soil of Non-Ricefields                                      Herbicidal Effect                                                        Dose                          Crop                                        Comp.                                                                             applied                                                                            Echinochloa                                                                         Digitalia                                                                           Amaranthus                                                                          Chenopodium                                                                          injury                                      No. g/a  crusgalli                                                                           ciliaris                                                                            viridis                                                                             album  Corn                                        __________________________________________________________________________    1   10.0 1.5   1.8   3     2.5    1                                               5.0  1.2   1.5   2     2      1                                           2   10.0 1.5   2     3     2      1.2                                             5.0  1.2   1.5   1.5   1.5    1                                           5   10.0 3     4.5   5     5      1.2                                             5.0  2.5   3     4.6   4.9    1                                           A   10.0 2.5   2.5   3     4      1.2                                             5.0  2     2     3     3      1.2                                         __________________________________________________________________________

Test Example 3 (Effect by Foliage Treatment)

Vats each having an area of 10×10 cm² and a depth of 5 cm were filledwith the soil of non-ricefields, which was sown with Echinochloacrusgalli, Abutilon theophrasti, Amaranthus viridis and Chenopodiumalbum. Fifteen days later, the wettable powders or emulsifiableconcentrates of compounds of the invention that were prepared inaccordance with the Formulation Examples were diluted, adjusted tospecified concentrations and thereafter sprayed to the stems and leavesof the grown plants using 20 liters of water per are. On the 10th dayafter the treatment, the herbicidal effect on the weeds under test wasinvestigated by the criteria for evaluation set forth in Table 1 and theresults were as shown in Table 4.

                  TABLE 4                                                         ______________________________________                                        Effect in Foliage Treatment                                                             Herbicidal Effect                                                         Dose      Echino-  Abutilon                                                                              Amaran-                                                                              Cheno-                                Comp. applied   chloa    theo-   thus   podium                                No.   ppm       crusgalli                                                                              phrasti viridis                                                                              album                                 ______________________________________                                        1     500       4        5       5      4.8                                         100       2.8      5       5      4                                     2     500       2        5       5      4.2                                         100       1.5      4.5     2.5    3.2                                   3     500       1.5      5       1.8    2.5                                         100       1.2      2.5     1.3    2                                     5     500       4.5      5       5      5                                           100       3        5       5      4.5                                   A     500       3.5      --      3.5    5                                           100       2.5      --      2.5    2.5                                   ______________________________________                                    

Industrial Applicability

The compounds of the present invention have potent herbicidal activityon their own; what is more, by hydrolyzing them, oxazolidinedionederivatives which are useful as an active ingredient in herbicides canbe manufactured in an industrially more advantageous manner andapplications that exploit their features are also feasible.

We claim:
 1. 4-Imino-oxazolidine-2-one derivatives represented by thegeneral formula (1): ##STR31## (where X¹ is a hydrogen atom or a halogenatom; X² is a hydrogen atom, a halogen atom or an alkyloxy group; X³ isa hydrogen atom, a halogen atom, an alkyloxy group, a cycloalkyloxygroup or an alkynyloxy group) and salts thereof. 2.4-Imino-oxazolidine-2-one derivatives according to claim 1, wherein X¹is a hydrogen atom or a halogen atom, X² is a hydrogen atom, a halogenatom or an alkyloxy group having 1-6 carbon atoms, X³ is a hydrogenatom, a halogen atom, an alkyloxy group having 1-6 carbon atoms, acycloalkyloxy group having 3-6 carbon atoms or an alkynyloxy grouphaving 3-4 carbon atoms, and salts thereof.
 3. 4-Imino-oxazolidine-2-onederivatives according to claim 1, wherein X² is a hydrogen atom, afluorine atom, a chlorine atom, a bromine atom, a methoxy group, anethoxy group, a propoxy group, an isopropoxy group, a butoxy group, anisobutoxy group, a pentyloxy group or a hexyloxy group, and saltsthereof.
 4. 4-Imino-oxazolidine-2-one derivatives according to claim 1,wherein X³ is a hydrogen atom, a fluorine atom, a chlorine atom, abromine atom, a methoxy group, an ethoxy group, a propoxy group, anisopropoxy group, a butoxy group, an isobutoxy group, a pentyloxy group,a hexyloxy group, a cyclopropyloxy group, a cyclopentyloxy group, acyclohexyloxy group, a propargyloxy group, a 1-butyn-3-yloxy group or a2-butynyloxy group, and salts thereof.
 5. 4-Imino-oxazolidine-2-onederivatives according to claim 2, wherein X¹ is a hydrogen atom, afluorine atom, a chlorine atom or a bromine atom, X² is a hydrogen atom,a fluorine atom, a chlorine atom, a bromine atom, a methoxy group, anethoxy group, a propoxy group, an isopropoxy group, a butoxy group, anisobutoxy group, a pentyloxy group or a hexyloxy group, X³ is a hydrogenatom, a fluorine atom, a chlorine atom, a bromine atom, a methoxy group,an ethoxy group, a propoxy group, an isopropoxy group, a butoxy group,an isobutoxy group, a pentyloxy group, a hexyloxy group, acyclopropyloxy group, a cyclopentyloxy group, a cyclohexyloxy group, apropargyloxy group, a 1-butyn-3-yloxy group or a 2-butynyloxy group, andsalts thereof.
 6. 4-Imino-oxazolidine-2-one derivatives according toclaim 5, wherein X¹ is a hydrogen atom, a fluorine atom or a chlorineatom, X² is a chlorine atom or a methoxy group, and X³ is a hydrogenatom, a chlorine atom, an isopropyloxy group, a cyclopentyloxy group ora 2-butynyloxy group, and salts thereof.
 7. 4-Imino-oxazolidine-2-onederivatives according to claim 6, which are selected from the groupconsisting of compounds represented by the following formulas: ##STR32##and salts thereof.
 8. A process for producing a4-imino-oxazolidine-2-one derivative represented by the general formula(1): ##STR33## (where X¹ is a hydrogen atom or a halogen atom; X² is ahydrogen atom, a halogen atom or an alkyloxy group having 1-6 carbonatoms, X³ is a hydrogen atom, a halogen atom, an alkyloxy group having1-6 carbon atoms, a cycloalkyloxy group having 3-6 carbon atoms or analkynyloxy group having 3-4 carbon atoms), characterized in that an arylisocyanate represented by the general formula (2): ##STR34## (where X¹is a hydrogen atom or a halogen atom; X² is a hydrogen atom, a halogenatom or an alkyloxy group having 1-6 carbon atoms; X³ is a hydrogenatom, a halogen atom, an alkyloxy group having 1-6 carbon atoms, acycloalkyloxy group having 3-6 carbon atoms or an alkynyloxy grouphaving 3-4 carbon atoms) is reacted with 1-cyano-2-methyl-2-propen-1-ol.9. A herbicide containing as an active ingredient4-imino-oxazolidine-2-one derivatives represented by the general formula(1): ##STR35## (where X¹ is a hydrogen atom or a halogen atom; X² is ahydrogen atom, a halogen atom or an alkyloxy group having 1-6 carbonatoms; X³ is a hydrogen atom, a halogen atom, an alkyloxy group having1-6 carbon atoms, a cycloalkyloxy group having 3-6 carbon atoms or analkynyloxy group having 3-4 carbon atoms, and salts thereof.
 10. Aprocess for producing a 5-isopropyliden-2,4-oxazolidinedione derivativerepresented by the general formula (3): ##STR36## (where X¹ is ahydrogen atom or a halogen atom; X² is a hydrogen atom, a halogen atomor an alkyloxy group having 1-6 carbon atoms; X³ is a hydrogen atom, ahalogen atom, an alkyloxy group having 1-6 carbon atoms, a cycloalkyloxygroup having 3-6 carbon atoms or an alkynyloxy group having 3-4 carbonatoms, characterized in that a 4-imino-oxazolidine-2-one derivativerepresented by the general formula (1): ##STR37## (where X¹ is ahydrogen atom or a halogen atom; X² is a hydrogen atom, a halogen atomor an alkyloxy group having 1-6 carbon atoms; X³ is a hydrogen atom, ahalogen atom, an alkyloxy group having 1-6 carbon atoms, a cycloalkyloxygroup having 3-6 carbon atoms or an alkynyloxy group having 3-4 carbonatoms) is hydrolyzed under acidic conditions.
 11. A process forproducing a 5-isopropyliden-2,4-oxazolidinedione derivative representedby the general formula (3): ##STR38## (where X¹ is a hydrogen atom or ahalogen atom; X² is a hydrogen atom, a halogen atom or an alkyloxy grouphaving 1-6 carbon atoms; X³ is a hydrogen atom, a halogen atom, analkyloxy group having 1-6 carbon atoms, a cycloalkyloxy group having 3-6carbon atoms or an alkynyloxy group having 3-4 carbon atoms),characterized in that an aryl isocyanate represented by the generalformula (2): ##STR39## (where X¹ is a hydrogen atom or a halogen atom;X² is a hydrogen atom, a halogen atom or an alkyloxy group having 1-6carbon atoms; X³ is a hydrogen atom, a halogen atom, an alkyloxy grouphaving 1-6 carbon atoms, a cycloalkyloxy group having 3-6 carbon atomsor an alkynyloxy group having 3-4 carbon atoms) is reacted with1-cyano-2-methyl-2-propen-1-ol in the presence of a base and thenhydrolyzing the imino group under acidic conditions.